Printing blanket mounting and tensioning apparatus



May 28, 1957 L. M. STEMPEL PRINTING BLANKET MOUNTING AND TENSIONING APPARATUS 2 Sheets-Sheet 1 Filed Oct. 23, 1953 y 8, 1957 L. M. STEMPEL 2,793,588

PRINTING BLANKET MOUNTING AND TENSIONING APPARATUS Filed 001.. 23, 1953 2 Sheets-Sheet 2 III/III INVENTOR. LB ZL O METEMPEL iii/fa BT'TORNEYS United States Patent 0 PRINTING BLANKET MOUNTING AND TENSIONING APPARATUS Application October 23, 1953, Serial No. 387,994

9 Claims. (Cl. 101-4151) This invention relates to the mounting and tensioning of printing blankets and more particularly to the assembly of blanket drum, blanket underlay, blanket, and attaching means for securing these parts together and tensioning the blanket to provide a highly effective surface for offset printing.

t is a general object of the present invention to provide a novel and effective combination of the elements mentioned above.

More particularly it is an object of the invention to provide mounting apparatus for a printing blanket facilitating its attachment to and tensioning over the blanket drum.

An important object includes the mounting and tensioning of a multipart underlay for imparting to the blanket a suitable cushioning resilience whereby its operation is improved and its life substantially lengthened.

Among the important features of the invention may be enumerated the following:

Uniform diameter of the drum;

All attachment means mounted below the drum surface;

Cushion layer of the underlay cemented to drum;

Filler piece supporting leading portion of cover ply of underlay to height of cushion layer;

Use of tensioned cover ply of underlay to immobilize and compress cushion layer;

Provision of blanket supports and deflectors at each end of cushion of underlay;

Radial disposition of all single thickness fastened ends of blanket and underlay cover ply;

Forward edge attachment of all plies of the underlay;

Uniform size of all lower plies of underlay;

Free trailing edges of all lower plies of underlay;

Use of tensioned top ply of underlay to position trailing edges of lower plies.

Other and further objects and features of the invention will be more apparent to those skilled in the art upon a consideration of the accompanying drawing and following specification, wherein are disclosed two exemplary embodiments of the invention with the understanding that such changes, modifications and combinations thereof may be made therein as fall within the scope of the appended claims without departing from the spirit of the invention.

In said drawings:

Fig. 1 is a section through a blanket drum of an offset printing press taken at right angles to the axis of rotation;

Fig. 2 is a fragmentary enlarged section through the drum at the leading edge of the blanket showing the latter and one embodiment of the underlay in position and illustrating the mounting and clamping means therefor;

Fig. 3 is a view similar to Fig. 2 but showing the trailing ends of the underlay and blanket as well as their securing and tensioning means;

Fig. 4 is a view similar to Fig. 2 but showing a second embodiment of the underlay; and

Fig. 5 is a longitudinal section through the drum taken on line 5-5 of Fig. 1.

In the operation of many types of printing presses what is generally known as a blanket is applied to the surface of one or more cylinders or drums thereon and used for various purposes, principally for its cushioning effect. Such a blanket usually takes the form of a rubber or synthetic elastomer, impregnated fabric or the like, in order that a smooth surface may be provided which in many cases takes the imprint of the ink from the printing cylinder and transfers it to the paper or other material being printed. Such blankets cover various portions of the arcuate surface of the blanket drum or cylinder and require that their ends be secured in such a manner that tension may be applied to insure their remaining tight on the surface of the drum. Usually the material of the blanket, While somewhat elastic or resilient, is reinforced to prevent it from stretching longitudinally. In accordance with the present invention there is provided a novel apparatus for mounting and tensioning the blanket on its drum or cylinder. Since for various purposes the requirement for additional cushioning means beneath the blanket is to be met, provision is made for mounting and tension ing a multipart underlay for the main blanket. Such underlay not only gives the surface of the blanket added resiliency and cushioning but tends to prolong the life of the very expensive blanket material.

While the drum and blanket assemblies shown in the accompanying drawings are intended primarily for offset printing, nevertheless the features of mounting are avail able for many other types and uses of blankets.

The drum or cylinder on which the blanket is mounted may take various forms but in general it is a relatively large diameter hollow cast iron or cast steel affair mounted for rotation on a horizontal axis. Such a drum from any suitable type of printing apparatus is shown at 10 in Figs. 1 and 5 and is provided with ends or heads 11 preferably perforated as at 12 for lightness and accessibility to the interior, and each head is fitted with a suitable hub 13 provided for mounting on a shaft about which the drum rotates. The cylindrical portion 14 of the drum is of suitable thickness to provide the necessary rigidity to sustain the load under which the drum is operated and the surface'15 thereof is substantially continuously cylindrical. The outer edges of the drum are provided with the radial flanges 16 to comprise bearers whose periphery is of substantially the same diameter as that of the blanket for well known purposes. In the case of the drum illustrated in Figs. 1 and 5 the blanket extends over slightly more than 180 of the periphery of the drum extending from the attaching slot 20 at the top, clockwise around to the adjusting slot 21 shown near the bottom. The blanket is not illustrated in Fig. 1 but in Figs. 2 and 3 the leading and trailing ends respectively of the blanket are seen with one embodiment of underlay, the direction of rotation of the drum as seen in Fig. 1 being counter-clockwise.

Referring now to Fig. 2 for an illustration of the attaching means for the leading edges of one embodiment of the underlay cover ply and of the blanket itself, it should be noted that in addition to the parallel walled transverse slot 20 in which the leading edge portion of the blanket is secured there is trailing it a shallow secondary slot 22 3. by spacer 23. Rivets 24'have thin flat heads 26 sunk in the cover ply as shown and the inner ends are countersunk in the underface of bar 23 as clearly seen in the drawing.

The main blanket 30 is seen to'rest on the cover ply ofthe underlay and to have its leading edge 31 bent downward at substantially a right angle to be clamped between the thin flat bar 32 and the blanket guide 33, both of which stand on edge in the slot near the trailing side thereof. The guide 33 has its rear face extending up to substantially the height of the top surface of the cover ply 27 of the underlay and then is provided with an arcuate surface 34 meeting its front face for bending andguiding the circumferential portion of the blanket down to connect with the radial edge 31.

The two bars 32 and'33 are connected together by a plurality of closely spaced screws 35, the fillister heads of which are recessed in bar 33 as shown, while the opposite ends are threaded into the thinner bar. The assembly of the leading edge'of the blanket and its clamp bars 32 and 33 is secured in position in the groove 20 by means of the heavy transverse locking bar 37 having a portion which closes the space in the slot between the forward face of the thin bar 32-and the forward edge of the slot. Above this it is widened to provide the overhanging hook-like flange 38 which engages over the upper edge of the thin bar 32and clamps it down into the slot. The locking bar is held in position by a plurality of heavy studs 39 as seen. The fillister heads 40 of these studs are recessed in the upper face of the locking bar and their threaded portionsare received in radial threaded holes in the material of the drum which is depressed beneath the several slots as seen at 42 in Fig. 1.

The trailing edge of the cushion layer 25 in the underlay is cut off as seen in Fig. 3 just short of the second guidebar 54 having the arcuate surface 55 for leading the longer trailing edge of the cover ply of the underlay down into its slot 21. This guide bar 55 is clamped in a shallow notch adjacent the slot 21 by means of studs engaging 'in the material of the drum as clearly seen in the figure.

The elongated trailing edge of the cover ply of the underlay is arranged between two clamping bars 56 and 57 not substantially different from those used to guide and clamp the leading edge of the main blanket. The thinner of these, 56, bears against the leading edge of the slot 21 and the thicker one 57 is held in place by studs 60 engaging in threaded openings in the material of the drum. The heads of these studs are in appropriate recesses in the top of the bar and the upper edge of the same is curved to an appropriate radius as at 61 to providea guide for the trailing edge of the blanket proper which, like the trailing edge of the cover ply, is turned inwardly at an angle so as to be substantially radial in the clamping portions. Tightening of the studs 60 provides the necessary tension in the cover ply to hold the cushion layer of underlay compressed against the drum as desired.

The trailing edge of the blanket after passing over the guide bar 54 above the cover ply of the underlay passes then over the curved surface 61 of the clamp bar 57 and is fitted between two thin clamp bars 62 and 63 of similar cross-section which, like the bars 56 and 57, are held together by appropriate studs or screws recessed therein for the purpose. Bars 62 and 63 are received in slot 21 behind bar 57. This slot, like the first one, is finally filled by a lock bar 66 closing the space between the trailing edge of the slot and the face of the clamp bar 63. This lockbar has an overhanging flanged portion 67 engaging the outer edge of the clamp bar 63 for drawing in and tensioning the blanket when the fastening studs 63 are tightened down into their openings in the material of the drum.

In assembling the apparatus the cushion layer of the underlay is first cemented to the drum-in the appropriate position and the leading edge of the underlay and its attached bar 23 and interposed spacer 28 positioned so that the bar fits into the notch 22 where it is secured by the studs 29 threaded into the material of the drum. The heads of these studs engage against the top surface of the bar 23 and pass through openings shown in dotted lines in the cover ply of the underlay" and in'the filler 28. The trailing edge of the cover ply is then secured between its clamp bars 56 and 57 which are inserted in the slot, with the material passing smoothly over the guide bar 54. The studs are tightened to provide the proper tension to hold the underlay appropriately in position. Next the leading edge of the blanket is secured between its calmps 32 and 33 and they are positioned in the slot 20 and drawn tightly to the-bottom thereof by means of the studs 40 acting on the lock bar 37. The blanket is then drawn over the cover ply of the overlay, cut to the appropriate length and its trailing edge fastened between clamp bars 62 and 63' by means of the screws 70. The clamping bars are now placed in the slot behind the clamp bar 57 and the locking member 66 fastened in position by means of its studs 68 which are adjusted to obtain the desired tension for the proper working conditions desired for the blanket.

In thesecond embodiment of the invention as illustrated in Fig. 4 only the underlay and itsleading edge mounting differ from the constructions shown in Figs. 2 and 3 and in describing Fig. 4 reference will be made only to those parts and arrangements which differ from those already described.

In Fig. 4 is will be seen that the single cemented underlay cushion 25 of Figs. 2 and 3 is supplanted by a stack of plies 75 of material similar to the cover ply 27 of the underlay of Fig. 2. The plies of this stack are not cemented together nor to the drum but as shown are all attached to the bar 23' by means of the long rivets 24' which also hold the leading edge of the cover ply 27. This construction avoids the use of the fnler 28 of Fig. 2 and provides for supporting the cover ply at its leading edge by the leading edges of the multiple plies which are cut off in superposed relation just behind the blanket guide 33.

The heads of bolts 29 for securing the bar 23' to the drum pass through enlarged holes 76 shown in dotted lines in all of the plies of the underlay and engage against the surface of the bar.

While not shown, the trailing edges of all but the cover ply of the underlay are. cut off in overlying relation just ahead'ofthe second guide bar 54 in the same manner as the trailing edge of the cushion 25 of Fig. 3. Not being cemented down however reliance is placed on the tension of the cover-ply 27' to hold these trailing edges in position. It likewise holds the main portions of the cushion plies smoothly against the drum face.

Installation of the underlay arrangement of Fig. 4 differs only in obvious ways necessitated by its construction from that already described.

Either of the apparatus shown provides for an effective and highly efiicient means for securing the underlay and the blanket in position on a blanket cylinder or drum and for giving to each independently the necessary tension to provide the proper working conditions. The arrangements contribute to the long life and smooth operation of the drum and the blankets.

I claim:

1. A drum and printing blanket assembly comprising in combination, a blanket drum having a substantially continuous cylindrical surface between widely spaced transverse main slots, a thick underlay cushion layer cemented to said surface and terminating close to said slots, a transverse bar mounted in a secondary slot in said drum between a main slot and the leading edge of said cushion, means securing said bar to said drum, a single cover ply of said underlay having its leading edge secured to said bar, a spacer between said cover ply. and the bar ems, ass

equal in thickness to the said cushion, means to secure the trailing edge of said single ply in the slot adjacent the trailing edge of said cushion layer, and a blanket covering said cover ply and having its ends secured in said main slots.

2. A drum and printing blanket assembly comprising in combination, a rigid blanket drum, an underlay covering a substantial portion of the circumference of the drum surface and including a cushion portion directly engaging the surface of the drum and a cover ply confining the cushion portion, means securing the leading edge of said cover ply to said drum at the level of the surface of the cushion portion, the trailing edge of the cover ply extending rearwardly beyond the trailing edge of the cushion portion, tensioning means securing the trailing edge of said cover ply to said drum, a blanket covering said cover ply, means fixedly securing the leading edge of the blanket to said drum in advance of the underlay, and tensioning means adjustably securing the trailing edge of the blanket to said drum circumferentially behind the trailing edge of the cover ply of the underlay.

3. The assembly as defined in claim 2 in which all means for securing the blanket and the trailing edge of the cover ply of the underlay extend below the surface of the drum and said drum having spaced transverse slots to accommodate said means.

4. The assembly as defined in claim 3 in which the blanket ends and the trailing end of the top ply of the underlay are clamped in radial position in said slots for attachment to the drum.

5. The assembly as defined in claim 4 in which certain of said securing means provide curved surfaces terminating adjacent the top level of the underlay to bend and guide the blanket ends into their radial attachment positions.

6. A drum and printing blanket assembly comprising in combination, a drum having a substantially continuous cylindrical surface, two remotely spaced transverse slots in said drum, a multi-part assembly of underlay having a cushion portion overlying said drum throughout the underlay length starting with its leading edge adjacent one of said slots and a cover ply partially above the drum surface, means securing the leading edge of the cover ply to means below the drum surface at a transverse position near the leading edge of the cushion portion, means tensioning and securing the trailing edge of the cover ply to the drum behind the trailing edge of the cushion portion and below the drum surface in the other slot, means secured to the drum in the slot adjacent to the leading edge of the cover ply forming a blanket support and deflector, means adjacent the trailing edge of said cushion layer forming a cover ply and blanket support and deflector, a blanket covering said cover ply and said deflectors, and means in said slots securing the blanket ends therein.

7. A drum and printing blanket assembly comprising in combination, a blanket drum having a substantially continuous cylindrical surface, a multi-ply assembly of underlay having all ply leading edges substantially in vertical alignment, a transverse bar mounted against the undersurface of said assembly adjacent said edges and secured to all plies, a slot in said drum closely receiving said bar, means securing said bar to said drum, a second bar secured to said drum adjacent the free trailing edges of the under plies of said underlay and projecting radially from the drum surface substantially the same distance, the top and trailing edge of said second bar being merged in a smooth curve to guide the top ply thereover, said top ply being longer than the under plies, a third bar, means clamping the top ply trailing edge to the radial side of said third bar, a second slot in said drum receiving said third bar, means to adjust said third bar radially in said slot to tension said top ply, and a blanket surfaced for printing covering said top ply, means securing the leading edge of said blanket in a slot in said drum in advance of the leading edges of the underlay and means securing the trailing edge of said blanket in a slot in said drum, said blanket being guided over the curved upper surface of the said third bar which adjusts the top ply of the underlay.

8. A drum and printing blanket assembly comprising in combination, a drum having a substantially continuous cylindrical surface, a multi-ply assembly of underlay secured to and above the surface of said drum at a transverse position near the leading edge of the assembly and having the leading edges of all plies in superposed relationship, the trailing edges of all plies except the uppermost being in superposed relationship, means tensioning and securing the trailing edge of the top ply to the drum behind the said superposed trailing edges and below the drum surface, means secured to the drum adjacent to the leading set of superposed ply edges forming a blanket support and deflector, means adjacent the trailing set of ply edges forming a top ply and blanket support and deflector, a blanket covering said top ply and said deflectors, and means securing the blanket ends to the drum below the level of the top ply.

9. A drum and printing blanket assembly comprising, in combination, a cylindrical drum having spaced transverse slots, a cushion covering one of the areas between said slots, a blanket covering said cushion and having its leading edge secured in one of said slots, two thin clamping bars in said other slot radially positioned to clamp the trailing edge of the blanket between them, a third bar in said other slot between one of the thin bars and the cushion end and having an arcuate trailing surface to lead the blanket end to said clamping bars, an adjusting member also in said other slot having a flange overlying the other of said thin clamping bars and means adjustably securing said member in said slot to determine the tension of the blanket.

References Cited in the file of this patent UNITED STATES PATENTS 1,071,527 Pannier Aug. 26, 1913 1,927,049 Schmidt et a1. Sept. 29, 1933 2,033,205 Poppe Mar. 10, 1936 2,042,076 Schultz May 26, 1936 2,164,480 Tornberg July 4, 1939 2,294,879 Afielder Sept. 8, 1942 2,329,830 Crafts Sept. 21, 1943 2,471,934 Chudner May 31, 1949 2,541,254 Huck et a1. Feb. 13, 1951 2,629,324 Smith Feb. 24, 1953 

